Humidifiers for fuel cells are known, for example, from DE 10 2009 034 095 A1 or EP 1 261 992 B1, which include a plurality of water-vapor-permeable membranes which separate flow channels through which moist or dry air is guided. Water molecules penetrate through the membrane from the moist to the dry air flow, which thereby is enriched with moisture. The moistened air flow is fed to a fuel cell system in which electricity is generated as a result of an electrochemical reaction.
In DE 10 2009 034 095 A1, a plurality of membranes arranged one above the other and spaced apart from one another are combined to a form a stack, wherein the membranes, in their edge region, are connected to frame parts, and a sealing element for a flow-tight closure is arranged between the frame parts of adjacent membranes. The dry or moist air flows crosswise through flow channels which are arranged one above the other and between which in each case one membrane is placed. The frame parts and the sealing elements therebetween also serve as spacers in order to fix the membranes, which are clamped in parallel, spaced apart from one another.